package edu.gyc.test;

import java.util.*;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.concurrent.CopyOnWriteArraySet;

public class ListNotSafe {
    public static void main(String[] args) {
        Map<String,String > map = new ConcurrentHashMap<>();

        for (int i = 0; i < 30; i++) {
            new Thread(()->{
                map.put(Thread.currentThread().getName(),UUID.randomUUID().toString().substring(0, 8));
                System.out.println(map);
            },String.valueOf(i)).start();
        }
    }

    private static void listNotSafe() {
        //   List<String> list = new ArrayList<>();
        //   List<String> list = new Vector<>();
        //   List<String> list = Collections.synchronizedList(new ArrayList<>());
        List<String> list = new CopyOnWriteArrayList<>();
        for (int i = 0; i < 30; i++) {
            new Thread(()->{
                list.add(UUID.randomUUID().toString().substring(0, 8));
                System.out.println(list);
            },String.valueOf(i)).start();
        }
    }
}
